The Expression And Function Of TrkB In Clear Cell Renal Cell Carcinoma

Objective:Recently, increasing evidences show that the abnormal expression of tyrosine kinase receptor B (kinase receptor B Tyrosine, TrkB) is closely associated with the malignant progression and prognosis of many kinds of neurogenic and non neurogenic tumors. Studies have reported that TrkB is different expressed in different types of cancer such as breast cancer, pancreatic cancer, non-small cell lung cancer, liver cancer and medullary thyroid carcinoma. However, the expression of TrkB in clear cell renal cell carcinoma (ccRCC) and the function are not understood. In this study, the expression of TrkB in clear cell renal cell carcinoma and cell lines was detected.Materials and methods:①Message RNA (mRNA) expression levels of TrkB were detected in 65 ccRCC tissue samples, their corresponding adjacent normal tissue samples and 24 metastatic ccRCC tissue samples by real-time quantitative polymerase chain reaction (PCR). TrkB protein expression levels in ccRCC and their corresponding normal kidney tissues were detected by western blot and immunohistochemical staining. ②The mRNA and protein expression levels of TrkB were detected in ccRCC cell line ACHN, Caki-1,769-P and 786-0, and human kidney epithelial cell line HK2. ③TrkB was over-expressed in cell line 769-P and 786-0. ④ We used MTS, wound healing and Transwell assays to detect cell proliferation, migration and invasion.Results: ①The mRNA expression of TrkB in ccRCC samples were significantly lower than their corresponding adjacent normal tissue samples (P=0.009), while the mRNA expression of TrkB in metastatic ccRCC samples were significantly higher(P=0.03), and the protein levels were lower in ccRCC samples.②Compared with human kidney epithelial cell line HK2, the expression of TrkB in mRNA and protein levels were significantly higher in metastatic ccRCC cell line ACHN, Caki-1 but lower in non-metastatic ccRCC cell line 769-P and 786-0. ③TrkB was successfully over-expressed in cell line 769-P and 786-0. ④ In cell function experiments, compared with the empty vector control group, MTS displayed that increased expression of TrkB inhibits proliferation; Wound healing and Transwell assay showed that increased expression of TrkB significantly promoted migration and invasion (P<0.05).Conclusions:The abnormal expression of TrkB in ccRCC may be related to the proliferation and invasion of the tumor, and play an important role in the malignant progression of ccRCC.